Studies on Hanoi Urban Transition in the Late 20th Century Based on GIS/RS

Abstract

This paper describes the urbanization process of Hanoi during the late 20th century using the methods of GIS (Geographical Information Systems) and remote sensing technologies. The data sources for the study compose of historical maps, recent maps, and various satellite images acquired from 1975 to 2005 (Landsat MSS, TM, ETM, JERS, ASTER, IKONOS and QuickBird).The main techniques used in our image processing are NDVI and Water Index, combined with a decision-tree classification for medium resolution images (Landsat and ASTER). High resolution images (IKONOS and QuickBird) were used to validate the signature of land use classes and to verify certain urban construction features. The analysis showed that the spatial growth of Hanoi is limited by natural barriers, such as streams to the northeast and east, water bodies to the north, and a swamp area to the south. The expansion of Hanoi stretches in four directions South, Southwest, West and East following main transportation axes connecting the inner city to neighboring areas. Both spatial expansion and in-fill expansion took place in the urbanization of Hanoi. It is important to relate the urban transition with social-economic mile stones of the city and to find correlations between remote sensing derived maps and in dices with other statistics such as population, population density, road and housing densities, but these have not been included in our present work.